1. Field of the Invention
The present invention relates to a process that increases the rate and quality of dispersion of hydroxypropylmethylcellulose in cold water.
2. Description of the Prior Art
Hydroxypropylmethylcellulose (HPMC) is a gum that poses unique problems to dispersibility in water. HPMC is easily dispersible in hot water but due to rapid surface wetting easily forms undispersible lumps of gum when added to cold aqueous systems. Use of HPMC has been inconvenient in many food formulating applications wherein the aqueous system had to be heated so that HPMC could be added and then cooled to ambient temperatures. When it is desired to combine HPMC with a heat-sensitive material, such as egg white, HPMC must first be dispersed in an aqueous solution that is heated; then the HPMC containing solution is cooled, and then combined with the egg white. HPMC has also been dispersed by blending with seven or more parts of a dry ingredient but the formation of lumps still occurs although the problem is somewhat reduced.
The difficulty of dispersing hydroxypropylmethylcellulose is well documented. For example, in the Hanson et al U.S. Pat. No. 2,716,072, methylcellulose is blended with sodium acetate and a finely divided solid synthetic anionic wetting agent of the group consisting of organic sulfates and sulfonates and their salts, to obtain a free flowing finely divided product. Another example of increasing the dispersibility of HPMC is to produce a composition containing HPMC and dioctyl sodium sulfosuccinate from 0.001% to 1.0% by weight of the composition, as described in the Whelan U.S. Pat. No. 3,503,895. A further example of an attempt to increase the dispersibility of hydroxypropylmethylcellulose is discussed in the Socha U.S. Pat. No. 4,373,959 wherein HPMC is lightly crosslinked with a dialdehyde such as glyoxal and a cellulose ether which has not been crosslinked.
A further known prior art technique which attempts to disperse a vegetable gums in general in an aqueous system is to first dry blend the vegetable gum with sucrose or other carrier materials. The vegetable gum and sucrose (or carrier) are then added to the water using high sheer agitation. The most effective high sheer system is to generate a vortex in the liquid with the vegetable gum and carrier being slowly added into the moving vortex to minimize localized particulate surface wetting and "fisheye" size. However, such a technique does not eliminate "fisheyes" but merely minimizes their size and occurence and is expensive in terms of time spent in reducing the "fisheye" problem. An additional problem with this technique in the case of HPMC is that HPMC is an effective foam stabilizer and thus the foam generated during high shear dispersion is difficult to dissipate.
Another technique used in the prior art which attempts to evenly disperse the vegetable gum in water, disperses the vegetable gum first thereby maximizing the water/vegetable gum ratio and preventing interference by other components in the gum hydration process. This technique is typically used for multi-component foods wherein several dry ingredients must be re-hydrated. The vegetable gum is typically dispersed in a vortex and slowly added thereto to minimize localized particulate surface wetting and "fisheye" size.
Another prior art process is disclosed in the Leo U.S. Pat. No. 2,949,428 wherein locus bean gum is rendered cold water soluble by agitating the locust bean gum with sugar in the presence of steam or a fine mist of water. The resulting mixture is a solid, foamy, spongy mass which is then heated. However, the physical state of the locust bean gum, being in a spongy mass, is not particularly suited for later use in a product such as a dry soup mix due to its high moisture content.
Another process which is highly successful in agglomerating gums and other food grade particulates used as thickening agents is described in patent application Ser. No. 06/524,145 entitled "Product and Process for Improving the Dispersion of a Vegetable Gum in Water," which will issue into U.S. Pat. No. 4,557,938 on Dec. 10, 1985. Agglomerated particles containing xanthan gum made by this process have been commercially available for more than one year.